Year	% of total fuel combustion
1971	17.37185485214761
1972	17.68767215559859
1973	18.46922952299396
1974	17.99024611545877
1975	18.574940007189422
1976	18.53729114160366
1977	18.468438757337903
1978	21.803058799515956
1979	23.30138811293996
1980	26.204722100014667
1981	25.938184150197923
1982	25.592715489489958
1983	25.381828466760048
1984	25.301301573377977
1985	27.554453801155198
1986	28.19341250804423
1987	29.194077150038243
1988	30.385208168562787
1989	33.13414120436133
1990	34.940316194109656
1991	36.31621059369499
1992	38.46956262573579
1993	40.12912308930008
1994	41.87602487546796
1995	41.067445308062126
1996	46.31714187229509
1997	45.69118557765086
1998	46.989188882851224
1999	49.40447454447648
2000	51.03849394076859
2001	51.22552194159188
2002	52.624024247276466
2003	53.75830943932567
2004	50.294651815537804
2005	50.22517352265452
2006	51.57791127166457
2007	51.334839075715344
2008	50.16206449894681
2009	50.36598678377104
2010	51.56823946905755
2011	52.39090372120495
2012	52.52680382833951
2013	53.15646287290517
2014	52.25300870698231